Ángulo ANB y Razón A:B en el diagnóstico cefalométrico de la relación intermaxilar según tipos faciales.

Abstract

Introduction: In orthodontics, the ANB angle is used to diagnose the sagittal intermaxillary relationship. The anatomical point Nasion at this angle is highly variable in its anteroposterior position. The A:B ratio, among other diagnostic tests, represents an alternative cephalometric measurement that relates points A and B, seeking more stable information that is less dependent on the Nasion point. Objective: To determine the agreement and correlation between the ANB angle and the A:B ratio in the cephalometric diagnosis of the intermaxillary relationship in different facial types. Method: This study employed a quantitative, radiographic, cross-sectional, descriptive observational design. It involved the objective measurement of cephalometric variables (ANB angle and A:B ratio) and statistical analysis of their agreement and correlation. Sensitivity, specificity, positive and negative predictive values, as well as positive and negative likelihood ratios, were analyzed. Results: The A:B ratio showed greater sensitivity and specificity in identifying Class II malocclusion, suggesting more stable behavior in this category. For the diagnosis of Class I malocclusion, its performance was moderate, with a better ability to rule out the class when it was not present. High sensitivity and specificity values were observed for Class III malocclusion. A moderate-to-high negative correlation coefficient (ρ = −0.698; p-value < 0.05) was found between the ANB angle and the A:B ratio, which was statistically significant; the level of agreement was moderate (Kappa 0.539). A statistically significant relationship was observed between facial type and skeletal class classification. Conclusions: It can be stated that the A:B ratio is a more consistent diagnostic tool for diagnosing Class II malocclusion and is less influenced by some geometric factors.